1. Field of the Invention
This invention relates to an architecture for an interface between a host device such as a personal computer, and a communication or information network.
2. Discussion of the Known Art
Network interface cards (NICs) are known which allow a laptop, portable or desktop personal computer to connect with a particular wired or wireless communication network for which a given card is dedicated. For example, if a number of host computers are to be linked with one another over a wired local area network (LAN) in a building using xe2x80x9cEthernetxe2x80x9d operating protocols, an Ethernet NIC must be connected to complete a data path between the network and each of the host computers. According to Ethernet protocols, data is transmitted in frames of between 46 and 1500 bytes in size, wherein each frame has six fields, namely; preamble, destination address (DA), source address (SA), type, data, and frame-check sequence (FCS).
Further, Ethernet uses broadcast technology wherein all host devices on the network will xe2x80x9chearxe2x80x9d a transmission from any one of the host devices. If two or more devices transmit data simultaneously, collisions of their data are detected and the devices must re-transmit their data after random waiting periods.
If the host computers are to operate over a xe2x80x9ctoken ringxe2x80x9d network, a different NIC which is configured according to token ring network protocols must be acquired for connection between the network and the computers. In a token ring network, certain signal frames have nine fields, namely; start delimiter (SD), access control (AC), frame control (FC), destination address (DA), source address (SA), information (I), frame-check sequence (FCS), end delimiter (ED), and frame status (FS) fields. Also, a host device cannot transmit data into the network until it captures a xe2x80x9ctokenxe2x80x9d frame, and changes a token bit in the access control or AC field.
Thus, a data packet in a token ring network has a substantially different frame format from that of packets in Ethernet networks; A dedicated Ethernet NIC will not operate on token ring frames to implement a token ring interface for a host device, and vice versa. And, if the host computers are to link with the Internet, a separate modem card is typically provided in addition to any NIC(s) installed in each computer for communication over LANs.
Emerging network technologies such as, e.g., asymmetric digital subscriber line or DSL may also require special interfaces to allow a host device to access wire lines of a network provider. Moreover, in a xe2x80x9cWaveLANxe2x80x9d network, a number of host computers are interconnected via wireless links currently assigned at 902 MHz, 2.4 GHz, or 5.7 GHz. Wireless LANs also require host devices to have interfaces adapted to meet special signaling protocols, in addition to a physical medium interface including a UHF or microwave transceiver and antenna.
A so-called xe2x80x9ccombo cardxe2x80x9d is offered by 3Com Corporation (No. 3CXEM556BT) which features both 10 Mbps Ethernet LAN and 56 kbps modem capabilities. These functions are performed using separate, dedicated hardware and software on the card, however. Also, future Ethernet or modem up-grades could be difficult, if not impossible, to implement on such a card.
Accordingly, as demand for access to various communication and information networks increases, there is a need for one interface architecture that will allow host devices and other networks nodes to select one of a number of different network protocols for communication with one another.
According to the invention, a reconfigurable network interface architecture includes a processor having an associated program memory. A programmable logic device is coupled to the processor, and has a connection port arranged to be coupled to a medium of a network having a defined network protocol. The logic device has an associated configuration memory, and the program memory and the configuration memory are arranged to store network protocol data corresponding to one or more network protocols. A data communication path is coupled to the processor and to the logic device, and the communication path is arranged to be coupled to a host device for transferring data between the host device and a network to which the logic device is coupled. In response to information identifying a selected network, the processor is arranged to load corresponding network protocol data from the configuration memory and the processor memory into the logic device and the processor, so that the host device can communicate with other devices over the selected network.
For a better understanding of the invention, reference is made to the following description taken in conjunction with the accompanying drawing and the appended claims.